Although open-source software can be customized to meet a company's specific needs, its inherent complexity could dent the profitability of independent software vendors, says Microsoft. "One of the beauties of the open-source model is that you get a lot of flexibility and componentization. The big downside is complexity," Ryan Gavin, Microsoft's director of platform strategy, said.

I don't think that a project is inherently more complex just because it's open source. I think it comes down to management - which is just as much of an issue for any other software project especially where 2+ people are involved.